**Core Concept**
Protein requirement for children is essential for growth and development, particularly during the toddler years. The World Health Organization (WHO) and other pediatric guidelines provide recommendations for protein intake based on age, sex, and weight.

**Why the Correct Answer is Right**
A 2-year-old child requires 20 grams of protein per day to support growth and development. This amount is crucial for the synthesis of new proteins, repair of tissues, and maintenance of various bodily functions. The Recommended Dietary Allowance (RDA) for protein in children aged 1-3 years is approximately 1.2-1.4 grams per kilogram of body weight per day, which translates to 20 grams for a typical 2-year-old child weighing around 12-14 kilograms.

**Why Each Wrong Option is Incorrect**
**Option A:** 10 grams is insufficient for a 2-year-old child, as it would not meet the requirements for growth and development.
**Option B:** 15 grams is still below the recommended amount, potentially leading to inadequate protein synthesis and tissue repair.
**Option D:** 25 grams is excessive and not necessary for a 2-year-old child, as it would lead to an imbalance in calorie and nutrient intake.

**Clinical Pearl / High-Yield Fact**
Remember that the protein requirement for children increases with age, and by 6-8 years, the RDA is approximately 0.8-1 gram per kilogram of body weight per day.

**✓ Correct Answer: C. 20 gm**